I've got an '08 FLHRC with factory installed Security System, and dealer installed SmartSiren.

I want to add the HD brake light mod (red lenses for turn signals, module to use turn signals as brake lights).

Instructions say to remove the maxi-fuse, and disconnect the battery cables. I have the service manual, followed the instructions, and when I pull the maxi-fuse, the siren goes off. Impressively in the garage! Even though the fob was in the fork lock.

What's the trick?

 

I don't have one, but I believe the pin # has to be entered with the ignition switch on, or something like that.
Ron

 

As soon as you remove the batt cables,,yes the alam will sound,,for approx 30 seconds,,I think,,when my friend did that to his the siren faded shortly after because its internal batt died down,,,

there is some instructions floating around on the forum here on how to disable for maint. but I dont remeber exactly where,,,do you have the owners manual?? it should say in there...

 

Install the module with the battery connected. I done it on two bikes.
Most of the disconnecting battery stuff is just B.S. Cover your ***.
In my opinion.
With the Ignition off there is no power right.
HD says to disconnect the battery before working on the clutch etc. I just did not try to start the motor when I was working on It. Duh

 

Follow up with solution:

With the fob near (I put the key in the fork lock) turn the ignition on, and then remove the Maxi-fuse. No alarm. Even removed the battery cables, no alarm. Did the mod. Put the Maxi-fuse back in, turned the ignition off. Alarm armed. Life goes on as normal.

 

Turn the ignition on, then pull the maxi fuse. the alarm should not trigger. Leave the ignition on until you have completed what your doing, then turn it off. The alarm should activate as normal (2 blips and flashes).